This is a continuous effort in response to the increasing demand of more precise measurement of relevant genomic information in any viral infection. The knowledge of the presence of specific viral gene will help in identifying the infectious agent. However, to assess the stage of a disease, to evaluate the efficacy of a treatment, to determine the value of a predictor in the progression of a disease and to monitor the patient's progression of an infection, a more precise and quantitative analysis of the specific gene would be required. These previously highly research oriented questions can now begin to be answered in the routine clinical laboratories with the advanced technology of molecular biology such as polymerase chain reaction (PCR), and the sequencing and mapping of the restriction nuclease digested fragments. We have adopted many of the published proven procedures and others, we initiated our own research to meet our needs. Then, we applied these technologies in conjunction with our current ongoing clinical research such as hepatitis B virus, hepatitis C virus and HIV infections. We have also improved the basic PCR technique to become a semi-quantitative procedure. We also conducted a genomic typing study based on PCR technology for HCV infected blood donors and post transfusion hepatitis C patients. During FY95, we were able to apply the same principles of using PCR a primary study tool for viral infection to a newly identified human hepatitis virus, HGV. This new hepatitis virus was identified through a joint effort of our group at NIH, scientists at CDC, and Genelab of California under a CRADA agreement. This virus was found to be causing post-transfusion hepatitis. Specific HGV RNA was identified in both recipients and paired donors' sera. It can cause chronic infection with mild or even no observed liver function abnormality. The prevalence in blood donors, in the preliminary studies, was higher than that of HCV.